They provide you with an on-line form listing your preferred travel dates, and alternate travel dates. You list the names of all the travelers (might have had seating preference there, too). In my case, getting to Athens, they held 4 tickets on a routing there, but could not make a reservation for the return flights until the magical 330 days arrived. They updated me via e-mail as flights were held in both directions, in case I wanted to change anything. When the flights in both directions were satisfactory, I authorized them to book the itinerary and received the confirmations from AA. I do recall talking to them by phone once or twice, but that may have been just to give final approval to book everything as reserved.

I could see using them again if I had a complicated booking (like RTW award travel) or a routing where specific timeframes needed to be met (i.e. 330 days out). I'd likely use them for the Olympics in Beijing in 2008 because of the timeframes I'd have to work with again. Just less of a headache.